Radiographic examination is often inadequate for an exact evaluation of the state of union of a healing fracture. Therefore, there is a definite need for additional non-invasive means to measure the rate of fracture healing. This has prompted several investigators to attempt to use ultrasonic and vibration tests to measure the degree of union of healing fractures. However, soft tissue effect makes such tests less reliable and therefore clinically less useful. We have developed a non-contacting electromagnetic device which can detect the propagation of stress-waves in a bone in a manner independent of the mechanical properties of the soft tissue. This device monitors the magnetic field produced by the piezoclectric charge associated with a stress wave propagating along a long bone. This method has been used to monitor the rate of simulated fracture healing of human long bones. The stress-wave was generated in embalmed human femora and the electromagnetic device was used to monitor the stress waves at two points along the length of the bone. After initial wave propogation studies were completed, simulated fractures were experimentally induced in the samples by making serial cuts of increasing depth into the bone cortex. The wave propagation studies were then repeated on each sample. A preliminary result of this study indicates that the changing charateristics of the stress waves as it propagates along the bone could be correlated to the degree of union at the point of simulated fracture. In future years, the sensitivity of this piezoelectric device will be improved so that it could be used clinically without a signal averager. This device will be used to measure the rate of fracture healing in experimental animals and the results will be compared with the strength of healing bone. Other possible methods of fracture healing measurements will also be evaluated.